ketay



March 1, 1949. M. F. KETAY 2,463,182

ELEVATIONAL CONTROL SYSTEM FOR AIRCRAFT GUN MOUNTS, Filed March 7, 1940 2 Sheets-Sheet 1 I INVENTOR F'IG.2. BY

' v ATTORNEY March 1, 1949. M. F. KETAY 2,463,182

ELEVATIONAL CONTROL SYSTEM FOR AIRCRAFT GUN MOUNTS Filed March 7, 1940 I 2 Sheets-Sheet 2 F iNvENToR FIG.3. $1 2 ATTORNEY Patented Mar. l, 1949 ELEVATIONAL CONTROL SYSTEM FOR li. CRAFT GUN MOUNTS Morris F. Ketay, Brooklyn, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind, a

corporation of Delaware Application March 7, 1940, Serial No. 322,705

'19 Claims.

This invention relates to fire control apparatus, and more particularly to means for controlling the elevation of one or more guns mounted on a vehicle, such as an airplane.

Heretofore, it has been customary to mount guns in a fixed position in the wings and fuselage of an airplane. In order to secure hits on a target with such guns, the pilot maneuvers his plane so as to use direct fire. and without making correction for range. When smaller guns, such as .30 calibre guns are being fired, no change in the elevation of the gun relative to the plane is desired because of the short ranges at which such guns are used. When larger guns of longer range are used, however, it is necessary, in order to obtain hits on a target, to vary the gun angle of elevation relative to the plane except when firing at point blank range.

It has been found that at certain speeds a plane noses down relative to its actual path through the air, while at lower speeds the same plane will nose up relative to its actual path, thus introducing a gun error which may be appreciable even at short ranges. This error increases as the range increases and when the plane is "nose down this error is added to the error which results from an increase in range of the target. When the plane is nose up the error introduced by this attitude of the plane causes the gun to shoot high at short ranges.

One of the objects of the present invention is to provide novel fire control apparatus for varying the angle of elevation oi a gun relative to the vehicle on which it is mounted to compensate for changes of range of the target.

Another object is to provide fire control apparatus for varying the angle of elevation of a gun to compensate for the nose down" or "nose up" attitude or "angle of attack of an airplane.

A further object of the invention is to provide novel fire control apparatus to vary the angle of elevation of one or more guns relative to an airplane to compensate for a variation in range of the target and, simultaneously, to compensate for angle of attack of the plane; the apparatus being adapted to compensate for range when the target is at a distance greater than a selected mimmum, such, for example, as 500 yards.

A still further object is to provide novel apparatus of the above character in combination with means for determining the range of the target or enemy aircraft.

Another object is to provide apparatus of the above type in combination with novel sighting means which is automatically maintained in the true path of flight of an airplane irrespective of the nose up" or "nose down" of the plane.

Other objects include the provision of novel means for causing the guns to automatically revert from a compensated position to a selected point-blank range position; to provide manual control means for determining the range of the target, and to combine the last mentioned means with novel mechanism for automatically controlling the elevation of the gun or guns relative to the vehicle on which they are mounted.

The above and other objects will appear more fully herafter in the detailed description which is to be read in connection with the accompanying drawings wherein like reference characters refer to like parts. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not designed as a definition of the limits of the invention, reference being bad primarily for this pur pose to the appended claims. In the drawings,

Fig. 1 is a view diagrammatically illustrating one embodiment of the invention adapted for compensating for angle of attack;

Fig. 2 is a view diagrammatically illustrating one form of the invention for compensating for range;

Fig. 3 is a diagrammatic view illustrating the circuits and principal elements employed in accordance with the present invention for compensating the large guns for range, and compensating all guns and the sight for the angle of attack of the airplane, and

Fig. 4 is an enlarged detail view of a portion of the sighting mechanism.

In the form illustrated, an airplane A is provided with a plurality of small guns 3, for example .30 calibre guns, mounted in the wings of the plane, and a plurality of large guns 4, for example .50 calibre guns, mounted in the fuselage. These guns are movable in elevation but not in azimuth. Conveniently located with respect to the pilot seat 5 is a gun sight 6, engine throttle lever I, and an air speed indicator 8.

' Compensation for angle of attack Each gun and sight 6 are moved in their respective vertical planes to compensate for the angle of attack, 1. e., the guns and sight are directed along the actual path of flight of the plane irrespective of its attitude. For this purpose a Pitot-static tube 9 is operatively connected to a static chamber l0 through a tube Ii and to a pressure chamber i2 through a tube It.

asaaisa effective through member M to move arm [9b in a counter-clockwise direction closing the con-.

pilot to inform the latter of the speed .of the plane.

The Pitot tube and chambers and i2 con stitute control means for the apparatus employed in elevating and depressing the guns and. gun sight to compensate for nose up and nose down. To this end pressure chamber [2 is pro vided with a pin i4 attached to the lower wall of said chamber. Pin 14, intermediate its ends, passes through and is secured to the lower flexible end wall l5 of the static chamber.. The outer or free end of pin l4 engages a bell-crank lever having arms Mia and H51), the parts being so arranged that an increase in pressure in chamber I2 is effective through pin l4 to move the lever in a counter-clockwise direction about a pivot shaft l1 and to close contacts l8 and I9 thereby closing the circuit through leads and 2i to the field 22 of a reversible-field motor 23. Preferably member [8 is a double contact secured to and movable with arm l6b. Motor 23 is energized through leads 24 and 25 by a suitable source of current 26, and is operative to rotate sight 6 about pivots 6a in a vertical plane relative to the fuselage by means of mechanical connections 21 and 28. The line of sight can thus be moved upwardly, relative to the plane, for example, to compensate for nose down.

Motor driven member 21 is also operative to move contact arms 4a, 4b, 3a, 3?) over resistances 29 and through suitable operating means to rotate a cam 30 which engages the free end of an arm 3| pivoted on shaft l1. Interposed between arm 3i and arm [6b of the bell-crank lever is a spring 32 having pre-selected characteristics. When cam 30 moves arm 3| in a clockwise direction spring 32 is compressed and after a predetermined compression the spring moves arm |6b and contact member [8 into entacts l8, l9 whereupon the armature of motor 23 rotates in one direction to move the sight through gagement with a contact 33, reversing the direction of the field of motor 23 whereby sight 6 is moved in opposite direction to compensate for "nose up of the plane; or arms 3| and I62; and member 18 may be moved to an intermediate position to breakthe-circuit to the field of motor 23, whereupon sight 6 will remain in the position to which it has been adjusted.

Resistances 29 with their associated arms, are

effective to control through suitable mechanism,

the elevation or depression of the guns. For this purpose the resistances are operatively connected to electric motors, one motor being provided adjacent each gun to elevate and depress the same. In order to simplify the illustration a circuit for only one of the resistances 29, with its associated motor 34, is shown. This circuit comprises a lead 35 connected to arm 4a and a lead 36 connected to said resistance. Lead 35 is also connected to an arm 31 adapted to be moved by motor 34 through a suitable mechanical connection 38 over a Wheatstone bridge arm 39. Lead 33 is connected to the adjacent arm 49 of the bridge and through lead H to a suitable source of power. The opposite arm 42, of the bridge is connected at one end through lead 43 to the coil 43a of a polarized relay mechanism while the opposite end of said arm is connected through lead 44 to the center contact member 45 of said relay, lead 44 being connected to a source of current 26 through lead 25. The relay controls the reversible field 34a of motor 34.

In operation, as the speed of the aircraft increases the increased pressure in chamber I2 is connections 21 and 28. Simultaneously, arm 4a is moved on resistance 29 through the mechanical connection diagrammatically shown at 210. When an unbalance is thus produced in the bridge, current will flow from the source of power through lead 44, arm 39, movable contact 31, lead 35, resistance 29, lead 33, arm 40 and lead 4i back to the source, a portion of the current flowing through the branch lead 43 and the winding 43a of the polarized relay whereby contact member 45 is moved to the right, for example, to close the field circuit 34a of motor 34. Motor 34 is operatively connected to the right-hand gun 4, for example, so that the gun is moved in elevation, through the same angle that sight 3 is moved, to compensate for the angle of attack of the plane which angle varies in accordance with the air speed of the plane, as pointed out above. Motor 34 is operatively connected through means 38 to contact 31 to move the latter and restore a balance in the bridge circuit, whereupon motor 34 is stopped and the gun remains in the selected angle of elevation relative to the airplane for that particular speed.

Compensation for range In Figs. 2 and 4, means are diagrammatically shown for correcting the angle of elevation of the gun relative to the plane to compensate for various ranges of the target and preferably such compensation is provided for the larger and longer range guns 4 only.

Sight 3, and its associated elements, constitutes means for determining the range of the target. As is understood in the art a pilot, upon sighting a target, will know the characteristics of the target including the wing spread or distance between the wing-tips thereof, and means are provided for solving a triangle having as its base the distance between the wing-tips whereby the range is obtained. For this purpose throttle lever ll carries, at the upper end thereof, a switch member 46 adapted to be moved forwardly and rearwardly by the thumb of the throttle hand of the pilot. Actuation of this switch member is efiective through an electrical pawl and ratchet mechanism 41, for example, or other suitable means, to move a pointer 43 along a pivot rod 49 and this movement is transmitted to any suitable means; such as a rack 50, whereby movement is transmitted through a. suitable connection 5i to the span setting scale 52 (Fig. 4) in sight 3. Assuming that the wing span of the target plane is 40 feet, for example, member 43 is actuated a sufficient number of times to bring the 40 foot indication on scale 52 opposite the pointer 53 which pointer and scale is viewed by the pilot in sight 3.

The grip 54 of throttle lever I is adapted to be rotated through a selected angular distanceand rotation of the grip is transmitted through suitable means, such as a Bowden wire 55, to a cam 56, which cam is engaged by pointer 43, the latter forming part of an arm 51 provided with an arcuate rack 58 which meshes with an elongated gear 59. Longitudinal movement of pointer 48 and arm 51 relative to cam 53 and rotation of cam 53 in the manner indicated is effective to move contacts 51a and 51b along resistances 4c and 4d, respectively, and through suitable means 33 to move arms 3| over resistances 32 and 33.

amass Member 60 is operatively connected through suitable means such as a Bowden wire 66 to the two stadia lines 65 (Fig. 4) of sight- 6 and the grip as is actuated until said stadia lines are moved to positions where they "sklrt the wing of the target B (Fig. 4) whereby the range triangle is solved, the movements of the stadia lines and scale 52 being combined within the sight and the result transmitted to the range scale 88 to bring the range 600 yards, for example, opposite the pointer 51. It will be noted that relative movement between cam 58 and pointer 48 is eflective to rotate shaft 80. When member 418 is actuated to adjust the position of pointer 48 relative to the cam, rackfil controlled by the spring is moved and this results in rotation of gear 59 and shaft 80. When member M is actuated cam 56 is rotated and this movement is eflective through pointer 48 to move rack 58 thereby rotating gear 59. Actuation of the control member 68 thus applies a correction based on the wing span of the target and the actuation of member 54 cooperates therewith to solve the triangle of which the wing span is the base.

The range correction is transmitted to suitable means, such as an electric motor 88, whereby the guns are elevated and depressed to compensate for range changes. For this purpose the electric motor, which is located adjacent the gun to be controlled, is operatively connected through suitable mechanical means 69 to gun 4, for example, ior elevating and depressing the same. The direction and extent of such movement are controlled by means including the resistances reierred to above.

In order to simplify the illustration, only one motor 88 is illustrated together with its control circuits. As illustrated, contact 51a is connected through lead Iii to arm 6! and resistance 62 is connected through lead ll, switch I2 and lead 73 to a contact i l adapted tobe moved along one arm of a Wheatstone bridge, the movement of contact 74 being obtained by means of a suitable connection 18 to motor 88. Resistance to engaged by contact 51a is in circuit through lead 11 with an arm 8| of the Wheatstone bridge and through lead 83 with the winding 85 of a polarized relay, the oppositeend of said winding being connected through a suitable lead to the Junction of arms 18 and 18a of said bridge. Lead 19 from a suitable source of direct current 80, such as a battery, for example, is connected to the junction of arms 18a and 8| of the bridge and the positive side of said source of current is connected through a lead 82 to the junction of arms 15 and 18 of the bridge and the same lead 82 operatively connects the positive side 01' said source of current to motor 68. Winding 86 is efifeotive to move a two-position contact member 85 of the relay into engagement with a stationary contact 88 which is connected by a lead 87 to the reversible-field winding 88 of motor 68. Alternatively, contact 85, which is connected to the source of current 80 through lead 89, is adapted to engage a contact '90 connected to said reversible-field through lead 9 I.

In operation, the pilot, after estimating the wing span of the target actuates member 46 to adjust span setting scale 52 and thereafter actuates grip member 54 to adjust the stadia lines whereupon the range is automatically determined and contacts 51:; and 6! are automatically adjusted to secure the proper flow of current in the Wheatstone bridge thus actuating the contact 85 in the relay to secure the proper direction of rotation oi the armature 01 motor 80 to elevate di' depress the gun. A balance in the Wheatstone bridge is re-established by motor 66 acting through means 16 to shift contact or pointer M. A range correction is thus automatically applied to the gun. a W During firing, it may be desirable for the pilot to quickly shift .his fire from a distant target to one close at hand and in order to readily accomplish this switch member 12 is moved from the position illustrated to engage acontact 92 thereby substituting a resistance 93 connected to lead W, for resistances 4C and 62 across one side of the bridge. The motor is now effective to quickly move the gun to a point-blank range position.

It will be understood that resistances dd and 83 are operatively connected to a second motor adapted to elevate or depress a .second gun through means as described above and other resistances and motors may be employed for controlling any number of guns as desired. The motor, arm 75 of the Wheatstone bridge, and pointer it are preferably located adjacent the gun, the remaining apparatus being mounted at any suitable position.

Combined compensation for range and angle of attack i In Fig. 3 there is illustrated means for combining the apparatus shown in Figs. 1 and 2 whereby a single motor 95 is adapted to elevate or depress the gun to compensate both for range and for angle of attack. For this purpose resistance 62 is operatively connected to resistance 29 through lead 95, and pointer 6a is connected -through lead 35 to switch 12 whereby a single Wheatstone bridge 96 and a polarized relayt'i are effective to control the flow of current to the reversible-field 98 of motor from a source 99.

There is thus provided novel means whereby guns, which are fixed in azimuth but movable in elevation, may be compensated for varying ranges or for varying angles of attack, or both, to increase the accuracy of fire. Preferably, the short range guns are compensated for angle of attack only. The sight is compensated for angle of attack but the larger or long range guns are compensated for both range and angle of attack. The speed determining means constitutes a torque amplifier as well as an indicator and is of the nullpoint type. When the member it moves outwardly from normal position, due to an in-' crease in speed, motor 23 is effective through cam 30, arm 3i, spring 32 and bellcrank lever lBa, l6b to return said pin it to its starting or normal position. The accurate operation of said means is not primarily dependent upon the deflection of the bellows member l2 but upon the amount of energy stored in a dependable and calibrated spring 32, and accordingly it will be understood by those skilled in the art that a portion of said means may be advantageously adapted for barometric uses.

As will be understood by those skilled in the art, various mechanical and/or electrical means may be employed in accordance with the present disclosure for compensating for range and angle of attack, the drawings merely diagrammatically indicating certain suitable means. Other means and circuits can be readily adapted by those skilled in the art if desired. For example. other means than a Pitot tube may be employed for determining the speed of the gun carrying platform. Accordingly, reference will be had pri- 7 marily to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. The method 01' controlling the fire of a gun mounted on an airplane which consists in determining the air speed of the airplane to determine the angle of attack of the latter relative to its true course, determining the range 01 the target, and elevating the gun relative to the longitudinal axis of the airplane at an angle which is a function of said speed and range to compensate for the range of the target and the angle of attack of the airplane.

2. The method of laying a gun and gun sight mounted on an airplane which latter assumes a nose-down attitude at certain speeds and a nose-up attitude at other speeds, which consists in determining the air speed of the airplane to determine the nose-down or nose-up attitude thereof, and moving the gun and gun sight in a vertical plane substantially parallel to the path of movement of the airplane through an angle which is a function of said speed.

- 3. The combination with large and small calibre guns mounted on an airplane, of means for determining the air speed of the airplane, sighting means mounted on said airplane for viewing a target including means for determining the range of the target, means for elevating and depressing the guns and sight relative to the airplane, and means controlled by thespeed determining means and the means for determining the range of the target for compensating the large calibre guns for range and angle of attack and the small calibre guns for angle of attack.

4. In a fire control system for one or more guns mounted on an airplane having a throttle lever, means for elevating and depressing said gun rela-- tive to the longitudinal axis of said airplane to compensate for changes in range of the target, a source of power for said means, means for determining the range of the selected target, a manually operable control for said range determining means mounted on said throttle lever, and means operatively connected to said manually perable control for controlling the direction and flow of power from said source to said first-named means.

5. Apparatus for controlling the elevation of a gun relative to a vehicle on which it is mounted, to compensate for the range of the target, comprising a range finder sight having stadia lines, a motor for elevating the gun, control circuits for the motor, means operatively connected to the sight for introducing into said circuits a correction corresponding to the width of the target, and means for moving the stadia lines to span the target and introduce a second correction into said control circuits.

6. Apparatus for controlling the elevation of a un relative to an airplane on which'the gun is ounted to compensate for range, comprising a sight having means therein for indicating the width of the target, the range thereof and stadia lines, means for adjusting the width indicator, means for adjusting the stadia lines, a motor for elevating the gun, and means operatively connected to said motor and adjusting means for actuating the motor in either direction through a predetermined angular distance.

'7. In apparatus of the class described, a gun sight having stadia lines and a span setting scale, means for adjusting the stadia lines, means for adjusting the span setting scale, a reversible motor for pivotallymoving said sight, means ineluding arelay for controlling the direction of mining means and the first-named means for a controlling the direction and period of flow of power from said source to said first-named means.

9. In apparatus for controlling the fireoi guns mounted on an airplane, a gun, a sight for said gun, means for elevating and depressing the gun, air speed determining means for the airplane, a motor controlled by said speed determining means, means operatively connected to said motor and said sight for moving the latter to compensate for the angle of attack of the airplane, and means controlled by said motor for determining the direction and period of operation of the gun elevating means.

10. The combination with a gun mounted on an airplane provided with a lever adjacent the pilot's seat, of power means for elevating the gun, I

sighting means having stadia lines and a span scale, means on said lever for adjusting said span scale for a target, means on said lever for adjusting said stadia lines whereby the range of the target is determined, aWheatstone bridge including a movable contact, means operatively connecting the bridge and contact to said power means, a source of power connected to said power means and bridge, and means operatively connected to said adjusting means and said bridge for controlling the operation of the power means.

11. The combination with a gun and sighting means therefor mounted on an airplane, of means for determining the air speed of the airplane, a reversible motor controlled by said speed determining means, means operatively connected to said motor and sighting means for moving the latter to compensate for the angle of attack of the airplane, a reversible motor for elevating said gun, and means operatively connected to said elevating motor and the means for compensating the sighting means to compensate said gun for said angle of attack.

12. In apparatus of the class described a Pitotstatic tube, pressure and static chambers operatively connected to said tube, a contact member,

means operatively connecting said contact member to said pressure chamber whereby movement of a wall in the pressure chamber is effective to move aid contact member, power means having a power circuit, said circuit being controlled by said contact, and means operatively connected to said contact and power means for restoring the contact to normal position and for moving said wall of the pressure chamber to its original position.

13. In apparatus of the class described, a Pitot tube, a static chamber connected to said tube, an expansible pressure chamber connected to said tube, a movable contact member, means operated by said pressure chamber for moving said contact member, power means including a circuit adapted to be opened and closed by said contact member, and means including a pressure spring operatively connected to said contact moving means and actuated by said power means for returning said contact member and pressure chamber to normal position.

14. In combination with a pressure chamber, power means including a circuit adapted to be opened and closed by the expansion and contraction of said pressure chamber, and yielding means operatively connected to said pressure chamber and power means and adapted to be energized by said power means for restoring said chamber to normal position to interrupt the control of the circuit by said chamber.

15. In an aircraft having a plurality of guns mounted thereon each having adjustable elevating mechanism for varying the angle of elevation of the gun with respect to the longitudinal axis of the aircraft, reversible power means for ac-- tuating the elevating mechanism of the guns, selector means for controlling the operation of said power means, and means responsive to change in air speed of said aircraft for controlling said selector means so that the plane of fire of the guns will remain parallel to the instant flight path of the aircraft irrespective of the alteration of the angle of the longitudinal axis of the aircraft with respect to the flight path due to change in air speed of said aircraft.

16. The structure as claimed in the next preceding claim, in which a follow-up is provided operatively associated with said power means and said selector means, whereby said selector means is actuated to de-energize the power means when the latter has eifected a change in the angle of elevation of each of said guns sumcient to compensate for the variation in the angle of the longitudinal axis of the aircraft with respect to the flight path with change in air speed.

17. In an aircraft having a gun mounted thereon, means for adjusting the angle of elevation of said gun with respect to the longitudinal axis of the aircraft, reversible power means for actuating said adjusting means, selector means for selectively controlling the operation of said power means, and air speed responsive means for controlling said selector means and operative to maintain the plane of fire of said gun substantially parallel with the instant line of flight of the aircraft. Y

18. The structure as claimed in the next preceding claim, in which said selector means has operatively ted therewith a restoring to the longitudinal axis of the aircraft, a gun sight associated with said gun, means for shifting said sight to vary the elevation angle of the line of sight thereof with respect to. the longitudinal axis of the aircraft, power means for simultaneously actuating said gun'elevation adjusting means and said means for shifting the gun sight, and means responsive to change in air speed of said aircraft for controlling the power means to. maintain the plane of fire of said gun and the line of sight of said gunsight substantially parallel with the instant line of flight of said aircraft.

MORRIS F. KETAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,299,509 Rey Apr. 8, 1919 1,612,118 Hewlett et al 'Dec. 28, 1926 1,724,092 Kauch et al Aug. 13, 1929 1,724,093 Kauch et al. Aug. 13, 1929 1,822,184 Wunsch Sept. 8, 1931 1,852,575 Howe Apr. 5, 1932 1,939,517 Paulus et al. Dec. 12, 1933 2,126,855 Wunsch Aug. '16, 1938 2,154,523 Midzette Apr. 18, 1939 2,160,202 'Fleux -1 May 30, 1939 40 2,190,569 Macgill Feb. 13, 1940 2,205,810 Van Ness June 25, 1940 2,208,875 Ohafee et al. July 9, 1940 FOREIGN PA'I'ENTS Number Country 8 Date 482,325 Great Britain Mar. 28, 1938 483,767 Great Britain Apr. 26, 1938 873,342 France Oct. 7, 1929 means actuated in response to the change in angle of elevation of said gun to tie-energize said power means upon a change in the angle of elevation of said gun equal to the change in angle of attack of the aircraft upon change in the air speed thereof.

19. In combination with an aircraft, a gun mounted thereon, adjusting means for varying the angled elevation of said gun with respect 

